Autoclave device

ABSTRACT

AN AUTOCLAVE DEVICE PROVIDED WITH DIFFERENT PRESSURE CHAMBERS BETWEEN WHICH GOODS TO BE TREATED CAN BE TRANSFERRED IN A PREETERMINED DIRECTION OF FLOW WITHOUT THE NECESSITY OF EQUALIZING THE PRESSURE DURING THE TREATMENT IN ONE CHAMBER TO AMBIENT ATMOSPHERIC PRESSURE BEFORE TRASFERRING THE GOODS TO A NEXT CHAMBER. THIS NEW DEVICE ENABLES AN AUTOCLAVE PROCESS TO BE PERFORMED CONTINUOUSLY AND EVEN AUTOMATICALLY WITH CONSIDERABLE SAVINGS IN STEAM CONSUMPTION.

Aug. 29, 1972 E. WIJARD ET AL 3,687,635

AUTOCLAVE DEVICE Filed Aug. 13, 1970 I 3 Sheets-Sheet 1 INVENTOR S 5N0 EL l/V/d/l R 0 AN oauAL z Au 29, 1972 g. WARD ET AL 3,687,535

AUTOCLAVE DEVICE 3 Sheets-Sheet Z Filed Aug. 13, 1970 INVENTOR5 5/1/05; WAN-L90 BY c/HN OOSV/ILL Aug. 29, 1972 E. WIJARD ET AL AUTOCLAVE DEVICE 5 Sheets-Sheet 3 Filed Aug. 15, 1970 United States Patent Ofiice Patented Aug. 29, 1972 3,687,635 AUTOCLAVE DEVICE Endel Wijard, Sodertalje, and Jan Odsvall, Tyreso,

Sweden, assignors to Aktiebolag Electrodius, Stockholm, Sweden Filed Aug. 13, 1970, Ser. No. 63,498 Claims priority, application Sweden, Aug. 22, 1969,

,715/69 Int. Cl. Btllj 3/00, 3/02 US. Cl. 23290 14 Claims ABSTRACT OF THE DISCLOSURE With the agglomerating of mineral particles, intended for e.g. blast furnaces, so-called green briquettes or balls are produced, as well as pellets via compressing or rolling of moist, finely divided material admixed with suitable binders.

Such green agglomerate bodies could not, however, be handled or transported for further industrial processes 'without after-treatment.

This after-treatment relates to a hardening of the agglomerate and can take place via drying, firing and sintering, storing during moist conditions or hydrothermal treatment, all dependent on the binder admixed in the primary mixture.

Hydrothermal treatmenti.e. a treatment with 'water vapour at high pressure and temperature has been suggested where hydraulic binders, such as cement, lime or slags are intended to be used for the after-hardening of the briquettes or the green balls.

Autoclaves are used to carry out hydrothermal treatmenti.e. cylindrical pressure chambers usually provided with suitably shaped closures at one or both of the end walls.

In the structural material industry, horizontally lying cylindrical autoclaves are usually used in which the product intended for hydrothermal treatment is conveyed stacked on carriages running on low tracks.

Similar autoclaves in combination with possibly cylindrically shaped carriage sides have been proposed as being usable equipment for hardening of dressed ore balls or other briquettes, micropellets or granulate of agglo'merate mineral particles.

The known autoclave process occurs in batches whereby complete pressure equalization to ambient atmospheric pressure ought to take place before the hardened product can be conveyed further for continued treatment in another pressure chamber, and in a possible other treating milieu. A transferring of the hardening product from the one autoclave or autoclave part to another during prevailing overpressure conditions would bring about such substantial advantages as higher production per time unit,

lower steam consumption and better prepared industrial processing for automation.

However, there is not yet known any proposed practical solutions as to how such advantages could be achieved in the autoclave process.

It could be conceivable to use a vertically erected autoclave construction which is divided up by intermediate partitions. In this construction, feeding would take place directly through an uppermost door, first to the upper half and then during the pressure treating step further to the lower part. The procedure then encounters the dumping problem which, because of the low strength of the unhardened balls or briquettes, allows only a very limited vertical drop.

The present invention relates to an autoclave device with which said essential improvements can be achieved and the present drawbacks in known constructions can be avoided.

The essential feature of the invention is chiefly that the axisymmetric shaped pressure chembers have their axes arranged in angular relationship to each other and to the horizontal plane, and are built together to form a unit so that the bodies, after treatment in an upper chamber, can descend by gravity to a lower chamber for continued treatment in the same unit.

The invention is illustrated by two embodiments schematically shown on the enclosed drawings. FIG. 1 shows a vertical projection of a simple embodiment having two pressure chambers whereby the longitudinal axis of one chamber is to be seen in the plane of the drawing. FIG. 2 shows the device illustrated in FIG. 1 as seen from the left in FIG. 1. FIG. 3 is a perspective view of a device having four pressure chambers. FIG. 4 shows a vertical projection of the same device as in FIG. 3, but with the longitudinal axes of the two upper pressure chambers to be seen in a vertical plane, at right angles to the plane of the drawing. FIG. 5 shows a perspective view of a device having four chambers whereby certain parts are cut away so that the insides will be seen. FIG. 6 shows a coupling diagram of the ducts to and from the chambers.

In the simple embodiments shown in FIGS. 1 and 2, a pressure vessel is formed having two chambers a, b, in the form of truncated cones. Said chembers are joined together where their bases lie adjacent to each other by means of a connecting part e, so that the shell of the device constitutes a unit. The longitudinal axes of said chambers form equal, circa 30 angles with the horizontal plane. This is made possible in that the longitudinal axis of one chamber forms an angle with the vertical plane which contains the longitudinal axis of the other chamber. The angles of inclination and the conicity of the chambers create angles of repose for the bodies which are treated in said chamber.

The agglomerate material bodies which are to be steam treated in the device are introduced into the upper end of the upper chamber a [whose end Wall is formed as a closure 1 which can be opened and closed by means of a hydraulic cylinder g. The lower, narrow end of the bottom chamber also forms an end wall closure h which can be operated in a similar way. The pressure vessel can be supported by a stand k.

The autoclave device shown in FIGS. 1 and 2 is unsymmetricallly built. A symmetric device having greater capacity can be obtained by building together two such devices into one unit, such as the embodiment shown in FIGS. 3 to where devices are also drawn in for steam supply and exhaust, as well as for condensation draining off.

The construction of the device shown in FIGS. 3 to 5 comprises essentially four monolithically built together, cylindrical or conical pressure vessels A, B, C and D arranged with three dimensional axes so that the longitudinal axes of the two upper vessels A and C incline at circa 30 angles to the horizontal plane and internally form a 120 angle, and that the longitudinal axes of the lower pressure vessels B and D incline circa 30" to the horizontal plane and that the internal complement of the angle of the axes thereby again becomes circa 120. Moreover, the pressure chambers are so oriented that the longitudinal axes of the upper chambers A and C coincide with a notional common vertical plane, the longitudinal axes of the lower pressure chambers B and I) also coinciding with another vertical plane but in such a way that these notional vertical planes form an internal angle of circa 90. Variations of said angle are possible between 80 and 100. All four longitudinal axes can have a common point of intersection, but this condition is not essential for the utilization intended for the construction.

Through the conical side surfaces of the pressure chambers are obtained favourable angles of repose, large volume content, good weight distribution in relation to the frame, long joining seams and thereby low tensile stresses in the structural material.

The four externally similar pressure chambers A, B, C and D are thus built together at their thick ends to form a unit since the side surfaces of the chambers are partially lengthened to common section lines.

The end wall sections of the chambers are constituted by customary spherical segments in the space obtained by the building together of said chambers. Said segments can touch each other at several points. All these end wall sections are provided with a least three doors 1, 2 and 3 intended for the transferring of treated material and, respectively, material to be treated, and to a certain degree even pressure medium or steam, from the upper chambers A and C to the corresponding lower chambers B and D. The centre space behind and between these end Wall sections is used for the location of valves or doors, their pneumatic or hydraulic operating means, and for short tube channels 1', 2 'and 3' arranged preferably between transferring openings in opposite end walls. These means can be reached from the outside through'manhole covers 4 provided at the two upper three-point intersecting places of the exterior casing. The two upper pressure chambers A and C each contain suitable U-shaped shelves or intermediate partitions 20, 21 fixed partially in the end walls and partially in the sides of the chamber so that the longitudinal inclination of said shelves corresponds with the longitudinal axis of the pressure chamber, and so that the lowest point in relation to the horizontal plane touches the doors 2 and 3 on the bottom side. The positioning of the shelves or intermediate partitions is further apparent from FIG. 5.

The introduction of live steam can take place through a trunk conduit 18 which first forks into two main lines 19, 22 which in turn branch oil in the vicinity of the upper three-point intersecting area of the exterior casing on both sides, so that the one end line 23 runs over the valve 6 in FIGS. 3 and 6 into the upper chamber A; the other end line 24 runs over the valve 7 to the lower chamber B. On the diagonally opposite side, end branches 25, 26 of the steam duct are connected to the pressure chambers C and D. Here are found valves 27, 28. Because a valve 8 in the live steam duct 22 is closed, the last part of the branch duct having the valves 6 and 7, 27 and 28 can, in open position, be used for pressure equalization as well as transferring of the steam already found in the chamber system, thus between the chambers A-B and, respectively, C-D. Another short transfer duct, controlled by valves 9 and and preferably diagonally on the opposite side of the upper three-point intersecting area, valves 30 and 31 are intended partly to take care of the pressure equalization in the system between the chambers B-C and D-A, and partly to blow out, when necessary, the rest of the steam no longer usable in the system. This latter function is performed by means of an outlet pipe 29 having valves #11 and 32.

Separate equalizing valves 12 and 13 facilitate the emptying of the residual steam from the upper chambers A and C separately and simultaneously with blowing out from any of the lower chambers, without first requiring any equalization of the pressure, between these chambers at different exhaust pressures. This leaves a greater flexibility when using difierent utilization systems. Condensation occurs during the first period of the steam hardening-i.e. during heating of the material and raising of the steam pressure. This condensate is continuously carried ofi from the device by means of automatic condensate separators :14, 15 of a known type. Said separators are provided with steam traps, are located at the lower threepoint intersecting places and are connected only to the upper pressure chambers A and C. Since only insignificant amounts of condensate are formed in the lower chambers, the condensate separators 16, 17 here are smaller and are preferably provided on the lowest part of the chambers B and D, e.g. at the bottom edge of the closure collar.

The monolithically integrated autoclave constructed according to the present invention is used in the followmg manner.

The cover to the chamber A is opened with the help of hydraulic operating means. Unhardened green balls, briquettes or granules are fed in directly from e.g. a conveyor belt to the autoclave, and roll down because of the downward sloping of the chamber sides and the intermediate partitions. By means of inserted semi-circular screens in the mouth of the autoclave, practically the whole chamber can be filled with bodies to be hardened. The shelves or intermediate partitions partially relieve the lowest situated unhardened bodies, thereby eliminating a risk of crushing in a chamber having a large diameter. The cover is then closed. The transfer valves 30 and 31 are opened while the valve 32 is closed. In this way, residual steam from chamber D is transferred in the beginning to chamber A. Thereafter, live steam is introduced over the valves 8 and 6, while valve 7 is closed. When the pressure in chamber A has risen to the same level prevailing with the admission of transfer steam from D, valve 30 is closed and valve 32 is opened instead. In this way blowing out of residual steam from chamber D occurs.

The increasing of the pressure in chamber A continues with live steam until the desired full pressure level has been reached. Thereafter, the other upper chamber C is filled with a new complement of unhardened bodies, and said chamber C is closed. Said chamber C is first fed transfer steam from chamber B, and then with live steam only. Full pressure prevails in chamber A at the same time as the pressure increase with live steam in chamber C takes place, while residual steam is blown out of chamber B. Thereafter, chamber B is opened at the bottom and the hardened product can roll directly onto the carriages of non-tracked conveying vehicles, or onto conveyor belts. The outflow can be controlled by opening the cover to different positions. This is done with the help of the covers hydraulic operating means.

As soon as chamber B has been emptied of its content of finished product, the cover is closed (see e.g. h in FIG. 1) and the transferring of steam from chamber A is undertaken through opening of both of the accessible tranfer valves 6 and 7. When the pressure in chamber A and B has almost been equalized, the door 1 in the lower part of chamber A is opened and the not completely fully hardened product is allowed to roll down to the lower chamber B along planes curved in several directions. In

this way only rolling sliding takes place, but a free fall is avoided. The intention is to further convey the balls or briquettes, which are not yet fully hardened during this stage, in a closed system from this upper chamber to the other one at a lower level without the risk of crushing needing to arise. At the same time with the outflow of solid substance in one direction, there occurs in a closed system an equalizing gas flow in the other direction. This equalizing pressure is channelled between the upper and lower chambers, partly through open transfer ducts and partly through the porous product and the appropriate doors.

After the hardening object has been moved out by rolling from the lowest part of chamber A intersection, the door 2 between A and B is opened and balls or briquettes situated between shelf partitions in chamber A are transferred by a sliding movement on top of the previous introduced product in chamber B. To start or facilitate the continuation of this movement, short pressure surges of steam are introduced in the upper chamber at the sides of the shelf partitions. This is made possible by the shelves crossing over the entrances of the steam ducts. By such connection means is received a distribution of possible initial steam jet on the top as well as the bottom side of the shelf partition. This results in that due to different turbulence conditions on both sides of the shelf plate said plate itself is set in vibration. This vibration in turn is capable of producing conditions for sliding.

Limited level differences between the midsections of the pressure chambers A and B, and the character of the angle of repose of the hardening product results in that a complete filling of the lower chamber B can take place first in connection with transferring of the hardening material through the door 3 out of the highest section in chamber A. This transferring operation is finally carried out identical with the preceding transferring of the material between the different sections in the chambers. Thereafter, all three doors between chambers A and B are closed. The pressure level in the chamber B, which is filled with the primary hardened product, is raised again slowly to desired full pressure, while the remaining steam is blown out of the chamber A. Whereafter, the cover is opened and a new batch of material to be hardened is supplied. The product transferred to chamber B can be secondary hardened during an almost equally long time in the lower chamber as in the upper cham ber. Through such a process is obtained the highest capacity utilization of the autoclave device proposed in the present invention, as well as the best steam economy.

It is of course also possible to use the same device according to an essentially different procedure than the above described procedure and a time-staggered, in parallel operating, system through the chambers A-B and 0-D.

If the device is supplemented by doubling the doors 1, 2 and 3 so that the transferring of the hardening product can take place in the inner part of the device from an upper chamber to two lower chambers simultaneously, possibilities arise for other utilization systems in other practically identical hardening devices.

The integral autoclave described in the present invention can be filled with balls, briquettes, pieces or granulate after short time intervals from a higher height level by means of a common conveyor belt alternately in chambers A and C, while the feeding out can take place unhindered over another conveyor path oriented in another direction and on a lower height level.

A conventional type hardening installation equipped with two cylindrical autoclaves, tracked autoclave carriages, similar cover diameters, and thus with the same capacity is estimated to cover circa four times the floor area and requires a at least two times greater steam plant than what is required for the comparable integral device described in the present invention.

The invention is also estimated to further result in essential economic advantages with the intended steam 6 hardening process as a result of the saving of tracked autoclave carriages, floor cranes, charging and extracting means for the carriages, reforwarder from the autoclave carriages to transport vehicles and shorter steam ducts.

By co-ordinating the feeding of the product to be hardened to two or more above described monolithic autoclaves over a conveyor belt, continuous production is achieved and automation is facilitated.

Instead of water vapour, gas or gas admixtures can be used as treating medium; and especially regarding the lower chambers, liquids can also be used e.g. for leaching or impregnating the material.

Although not presently contemplated it is obvious that the chambers, the interior of the chambers, the transfer ducts, the valves etc., can be given any other suitable configuration and design to provide for autoclave treatment of goods other than agglomerates.

Having described our invention, we claim:

1. An autoclave for fluent material comprising a plurality of closely spaced pressure chambers mounted as a unit, at least a pair of said chambers being disposed one higher than the other and having axes disposed at an angle to each other and to the horizontal, and means for selectively establishing communication between said chambers of said pair for the flow of said material by gravity from the upper to the lower chambers of said pair for continued treatment in the same said unit.

2. An autoclave as claimed in claim 1, said chambers being in the form of truncated cones whose larger ends are in unitary assembly with each other.

3. An autoclave as claimed in claim 1, in which at least two of said axes lie in a common vertical plane.

4. An autoclave as claimed in claim 1, in which said axis of one said pressure chamber forms an angle with a vertical plane containing the longitudinal axis of another said pressure chamber.

5. An autoclave as claimed in claim 1, and conduit means communicating between said pressure chambers, and valve means for selectively opening and closing the conduit means thereby to permit flow of a treating fluid between said chambers.

6. An autoclave as claimed in claim 1, said chambers having common end walls between them, said means comprising doors through said end walls for selectively transferring material from chamber to chamber.

7. An autoclave as claimed in claim 1, there being a plurality of pairs of said chambers, said means for establishing communication between said chambers permitting transfer of material from one chamber of one pair to the other chamber of said one pair but preventing transfer of material between chambers of diiferent pairs.

8. An autoclave as claimed in claim 7, and a steam supply common to all said chambers, and means establishing communication between said steam supply and said chambers.

9. An autoclave as claimed in claim 1, there being two upper chambers whose axes lie in a common vertical plane and two lower chambers whose axes lie in a common vertical plane, the two said vertical planes being disposed at an angle to each other of to degrees.

10. An autoclave as claimed in claim 9, the last-named angle being about 90 degrees.

11. An autoclave as claimed in claim 1, said angle between the axes of the chambers being to 130 degrees.

12. An autoclave as claimed in claim 11, the last-named angle being about degrees.

13. An autoclave as claimed in claim 1, said upper chamber having a door at an upper end thereof, said upper chamber having longitudinal partitions therein that are bent in cross section and disposed one above the other and that extend downwardly from said door to provide plural separate paths of movement for material downwardly through said upper chamber.

14. An autoclave as claimed in claim 13, and a steam duct communicating with said upper chamber adjacent 8 the lower ends of said partitions to supply steam to said FOREIGN PATENTS chamber- 698,299 11/1964 Canada 23-252 R References Clted UNITED STATES PATENTS BARRY S. RICHMAN, Primary Examiner 640,936 1/1900 Parsons 34-211 x 5 US Cl XR 2,173,315 12/1956 Liljenstrom 34-410 x 3,338,663 8/1967 Beecher et a1. 21-94 X 2194, 23252 10, 211 

